It can be appreciated that numerous attempts have been made to improve the performance of a bat. These prior attempts have included the addition of various shells, inserts, materials, and shapes of the bat in order to improve its performance or usage. For example, U.S. Pat. Nos. 6,949,038, 6,761,653 6,743,127, 6,733,404, 6,702,698, 6,497,631, 6,176,795, 6,022,282, 4,930,772, 4,331,330, and 3,990,699, and U.S. Patent Application Publication Nos. 2002/0016230, 2002/0091022, and 2005/0070384 disclose various attempts to improve the performance or use of a bat.
The performance of a bat is generally based upon the weight of the bat, size of the bat, and the impact response of the bat at and during impact with a ball. Most of the focus for improvements in bat technology has been in improving the performance of the preferred impact area, or sweet spot. As the prior art bats have increased the performance in this area, many of the sports regulatory agencies have placed performance and/or configuration restrictions on the bats. These restrictions have mandated new innovations in the development of the bat technology.
For example, one regulatory body requires a maximum performance from a bat when impacted in the preferred impact area, or sweet spot of the bat. Typically, this location is approximately six inches from the end of the bat. As such, the current maximum performance for the bat in its preferred hitting area is limited by these regulations. However, it is also to be understood that the area to either side of the sweet spot on a prior art bat has a significant drop off in performance.
The contemporary bat art has made few attempts to improve the performance of the bat sections adjacent the preferred impact area. As such, the performance of the bats in areas distal from, and even adjacent to, the sweet spot dramatically drops for the conventional bats. The portion of the prior art that has attempted to address this need has drawbacks.
For example, U.S. Pat. No. 6,949,038 issued Sep. 27, 2005 discloses increasing the thickness over the sweet spot of the barrel in order to increase the leaf spring effect of the bat. However, this patent fails to reduce the thickness of any wall within the bat in order to increase performance of the bat or vary, or stack, wall layers along the axis of the bat. As such, this patent increases the weight of the bat in an attempt to increase the performance of the bat, which is counter productive. This patent also increases the cost of the bat by increasing the amount of material used.
U.S. Pat. No. 6,761,653 issued Jul. 13, 2004 recognizes the advantages of placing a more durable material in the sweet spot than on either side of the sweet spot to provide the most durable material at the point(s) of maximum bending or deflection. However, the '653 patent fails to recognize any performance benefits and simply uses concentric layers of material stacked in a radial direction along the barrel length.
Thus, there is a continuing need for improved overall performance of bats. These improved bats need to conform to the regulatory agencies' restrictions in the preferred hitting zone while performing well at location that are longitudinally outside the preferred hitting zone. This needed bat should increase the performance in area(s) adjacent the preferred hitting zone as compared to the preferred hitting zone. As such, what is needed is a bat that varies the stiffness of the wall of the bat in order to enhance performance of the bat.